Radio telegraph system



April 27 1926.

J. B. BRADY RADIO TELEGRAPH SYSTEM 2 Sheets-Sheet l i'led Feb. 24, 192537 mul/mm April 27 1926.

J. B. BRADY RADIO TELEGRAPH SYSTEM 2 Sheets-Shut 2 Filed Feb. 24, 1925Mull" "El will. IIIIIIIIIIIIIIIJI to provide an electronic controlcircuit for Patented Apr. 27, 1926.

UNITED STATES PATENT OFFICE.

JOHN-B. BRADY, 0F SOMERSET, MARYLAND, ASSSIGNOR TO MORKRUM COMPANY, OF

CHICAGQ, ILLINOIS, A CORPORATION 0F MAINE.

RADIO TELEGRAPH SYSTEM.

To 7l whom t mayconcem:

Be it known that I, JOHN B. BRADY, a citizen of the United States,residing at Somerset, in the county of Montgomery and State o'tl\laryland, have invented certain new and luseful Improvements in RadioTelegraph Systems, of which the following is a speciication.

This application is a continuation in part of my application Serial No.657,061, filed August 13, 1923, allowed April 14, 1924.

My invention relates broadly to radio communication, and moreparticularly to radio telegraph systems employing automatic means fortransmitting signals and automatically recording the signals in print atthe receiving station.

.One of the objects of my invention is to provide means forautomatically controlling the speed of automatic transmitting appa ratusand correspondingly controlling the speed of automatic printingreceiving apparatus at a distant radio receiver.

Another objectl of my invention is to provide means for maintainingconstant speedof bot-h an automatic radio transmitting apparatus and anautomatic printing receiving apparatus so arranged that no interferenceis oiieredto the operation of electron tube circuits employed in highamplilication radio receiving apparatus and relay apparatus associatedwith the receiving printer or with the electron tube modulator orloscillator circuits at the transmitter.

A still further object of the invention is governing the speed ofautomatic printer transmitting apparatus and automatic printerkreceiving apparatus situated at distances one from the other.

Other and further objects of my invention will be understood from thefollowing speciication by reference to the accompanying drawings, inwhich Figure 1 represents a radio transmitting' installation with anautomatic transmitting apparatus undercontrol of an electron tubecircuit; Fig. 2 shows a radio receiving circuit having an automaticprinter apparatus connected therein and under control of an elect-rontube circuit; Fig.v 3 is a diagrammatic view of a portion of the frameof the rotative mechanism ot thc automatic apparatus at both the radiotransmitter and receiver showing the arrangement of the electron tubecont-rol circuit with reference to the driving motor on the apparatus;Fig. 4

is a side elevationof the driving motor and centriugalfgovernor showingthe slip rings and brush connections by which electrical connections arecompleted with the electron tube control circuit and Fig. 5 is a frontelevation of the governor illustrated in Fig. 4.

My invention employs automatic apparatus known as the teletype,manufactured by the Morkrum Company of Chicago, Illinois, the inventionof Charles L. and Howard L. Krum, in combination with radio transmittingand receiving apparatus. The details of construction of this equipmentare .set forth in an application for patent filed by Charles L. andHowardL. Krum, Serial No..477,012,'tiled June 15, 1921, and Serial No.673,273, filed November 7, 1923, and also in John B. Bradys Patent No.1,485,212, dated February 26, 1924.

Heretot'ore, various mechanical devices have been used for controllngthe speed of the individual units of apparatus which have in generalincluded -a -make-and-break contact device producing a spark dischargeacross the contacts thereof, which spark discharge occurring in anassociated "circuit lforms-in itself a minute radio transmission ceived.This interference-has been particularly objectionable where theautomatic print-er receiving apparatus has been` employed at acentral'radioreceiving center where a great many channels of radioreception are being operated simultaneously on separated frequenciessome actuating photographic recording apparatus, some connected to inktape recorders and still others connected to a local telephone circuitwhere the signals are translated mentally by an operator and copied downby hand or on the typewriter. In such installations as these it has beenfound that the sparking at the governor has a tendency to reduce theefliciency of the other means of recording and act'ually interferestherewith. This spark discharge and resulting electrical disturbance isparticularly objectionable in` radio printer systems as it often tendsto actually annul the printer 'signals and render the systeminoperative. By my present invention I eliminate this undesirableinterference in the electron tube circuits.

I have illustrated the invention at the transmitting station inconnection with a d i rect automat-ic keyboard control, but it w1ll beunderstood that automatic tape impulse transmission may be used and thespeed of the apparatus imaintained at a predetermined constant value bythe electroniclcontrol circuitto be hereinunder described.

Referring to Figure 1 of the, drawings reference character 1 indicates aradio transmitting antenna system having ground connection 2. The radiotransmitting apparatus has been represented diagrammatically lat 4. Asource of sustained oscillations is provided which may be Aan electrontube generator as shown, an alternator, an arc generator or other sourceof continuous wave energy. I have illustrated by way of. example,electron tube oscillators 5, 6 and 7 having their grid, filament andplate electrodes connected in parallel and the grid and plate circuitsinterlinked through antenna inductance 8. It will be clear that a singletube oscillator may be used and the other tubes arranged to increase theamplitude of the oscillations. The signaling. impulses may be producedby changing the condition of the oscillator circuit'by means of relay 9.The control coils l0 of this relay l.are connected through alocal-battery 11 with the contacts 12' and 14 of the transmitter 15. Thedriving motor 16, through the medium of a distributing cam shaft or thelike, opcrates the transmitter contacts 12 and 14 and causes radiationor suppressionof impulses of energyfrom the antenna.r system 1 through adefinite number of successive timed impulses for each character signal.The speed of the motor which thus determines the timing of thetransmitted impulses during each signal period, is uniformly maintainedat the desired rate by means of the electron tube circuit 18. In thearrangement shown, motor 16 is a series wound, direct current machineand its armature 19 is supplied with current from a source 20, .whichalso supplies the series field coils 21.

- The motor 16 is provided with a centrifu al type of governor as shownin Figs. 4 an 5 housed within the chamber 22, forming a fly wheel forthe motor. A movable arni member 23 is provided within the fly wheelhousing 22 mounted on spring. strip 24,

mounted on post 25 within the fly Wheel housing. The arm member isarranged to be actuated by centrifugal force `against the action of coilspring 26, the tension in which is adjustable by screw 27.

The arm member 23 is shown arranged to make successive connection with acontact 28 or a contact 29. located opposite contact 28. The arm 23 isconnected with the filament circuit 34 of electron tubes 30 and 31. Adivided grid circuit 35 is provided, one path being completed throughnegative battery 32 to contact 28'toward which arm 23 is pressed by itsspring and the other circuit being completed by arm 23 moving to theother contact 29 under centrifugal-action. The contact 29 contacts topositive battery 40. The relatively large negative charge from battery32 onthc grids ofthe tubes 30 and 31 has thetendency of preventing anycurrent flow in the plate circuit 36. The plate circuit contains highpotential battery 37 and auxiliary field coils 38 wound in the samedirection as the main field coils 21 in such manner that when currentflows through the auxiliary field Winding 38 the 'fiux through the fieldcoils 21 is increased. The arm 23 moves olf of contact 28 immediatelyupon any increase in speed of motor 16- is accordance with centrifugalaction. The arm then connects with contact 29 placing a positive chargeon the, grids of tubes 30 and 31 of battery 40. A current now commencesto pass in the plate circuit 36 and inasmuch as the iiow of currentthrough the auxiliary field winding 38 isin the same direction as thatthrough the main field Winding 21, the flux in the field increasescausing the motor speed to be reduced, whereupon arm 23 returns'tocontact 28 returning negative polarity to the grids and stopping furtherpassage of current in the plate circuit 36. Y,

At the distant receiving station an antenna system 41 may be employedhaving radio receiving apparatus coupled therewith. I have shown by wayof example two stages of radio frequency amplification obtained by meansof electron tubes 42 and 43, a detector 44 which may be coupled with'alocal oscillator for lieterodyne reception, and tubes 4 5 and 46 servingas an audio frequency amplifier of'the received impulses. The impulsesoperate a power tube relay 47 having an input circuit selectively tunedto the tone frequency of the incoming impulses. The output circuit ofthe power ,tuberelay 47 includes the windingsof a sharply responsivemechanical relay 48 which closes a local circuit 49 through teletypemagnet coils .50. The magnet 4coils'() attract an armature whichoperates to contro'lthe'fautomatic printing of characters representedlsigna-l period by a motor 16similar t-o that at the distant transmitterwhich cll'ects and times the operation ot the transmitter contacts.Preferably, the motor operates the rotary distributing member of theprinting appara-tus through the medium ot the clutch which, in responseto received impulses, is

vtripped into operation at the beginning ot' each signal period. In suchcases, it is desirable that the receiving distributor rotates slightly'faster than the transmittingr distributor and this is preferablyetl'eeted by intcrposing suitable gearing between the motors and 4partsoperated thereby, so that both motors may be set for operation at thesame speed. An electron tube control circuit 18 is arranged at thereceiver and adjusted and set with respect to the electron tube controlcircuit 18 at the transmitter. Tubes and 31 having characteristicssinrilar to the characteristics of tubes -30 and 31 are employed. Thegrid circuit is divided as at the transmitter and contains a correspending source of negative potential 32 normally connected` With the,grid circuit through contact 28 whereby no current flows in the platecircuit 36. Should motor 16 tend to run faster than motor 16 or increaseabove normal speed, arm23 moves .to contact 29 placing a positive chargefrom batte '40 on the grids of the tubes 30 and 31 thereby causing apassage of current in the plate circuit 31 through auxiliary coils 38increasing the field of coils 21 and bringing the motor 16 back topredetermined speed With the motor 16 at the distant transmitter.

Figure 3 of the drawings shows on enlarged scale the electron tubecontrol circuit for the motor 16 wherein the motoris i1'- lustrated asdriven from a source 61 with auxiliary coil 38 coupled -with the fieldwinding 21. f y U In Figures 4 and 5' the cylindrical housing 22 for thecentrifugal governor is illustrated as having three slip rings 52, 53and 54 which areconnected interiorly of the cylindrical housing 22 withthe terminal-s 25,

28 and 29 and to which sliding connection is made from the exterior ofthe 'motor through brushes 57, 58 and 59. The brushes are carried oninsulated blockV 56|' and contact with the slip rings 52, 53 and 54.Connections such as the leads 60, represented in Fig. 5,are takenfromthe terminal block 56 to the electron tube circuits asclearly set forthin Fig. 3. The usualispeed control spots 55 are provided on the exteriorof the governor whousing 22 for initially setting the speed ottlle'machine. l

Both the transmitting and receiving machines are initially adjustedthrough procproduction ot sparking which has been heretot'ore acontinuous source of' interference in the operation ot' radio printersystems.

The operation ot' this system has been de,- scribed in conjunction withthe preceding description. It will be clear that this automatic printingapparatus may be used side by side with i:'zanual receiving apparatuswit-hout interference in the telephone receivers ot' the latter type ot'system by the automatic printing apparatus. lt will also be understoodthat a Aconstruction ot electron tube may be employed` which controls arelatively large plate currentand thereby permit speed control apparatusat both the transi'nitting and receiving station to be small andcompact.

While I have described my invention in a particular embodiment, it willbe understood that modifications may be made and that I intend nolimitations upon the invention other than those imposed by the scope ot'the appended claims.

lV hat I claim and desire to secure by Letters Patent ot' the UnitedStates is as follows:

1. A system'ot radio communication comprising in combination a radiotransmitter, means for automatically transmitting signals in groups ofimpulses of energy, a radio receiver, electrical means for receivingsaid impulses of energy/,mechanical means for automatically receivingsaid impulses and causing characters represented by particular groups ofimpulses to be simultaneously printed and electron tube circuits at bothsaid transmitter `andreceiver for maintaining said automatictransmitting means and said/automatic receiving means Within apredetermined range of speed.

2. A system of radio communication comprising in combination means fortransmitting radio frequency energy in groups ot impulses of energy, anelectron tube circuit for maintaining the radiation of said impulses otenergy at predetermined speed, a receiving apparatus having meansyautomatically responding to said impulses of energy forvprinting acharacter represented by each particular group of impulses and anelect-ron tube circuit for maintaining said means at `substantially thesame speed as said transmitting means.

3. A system of radio communication comprising in combination atransmitting apparatus, a source ot oscillations, rotating mechanism forcausing radiation ot' said oscillations in groups ot' impulses ot'energy, Aan electron tube circuit, for maintaining said rotatingmechanism at'predetermined speed whereby the speed of transmission ofesses of `factory inspection to operate at aasaid impulses ispredetermined, afreceiving predetermined speed and the electron tubecircuits are arranged to maintain the machines` at this selected speedLWithout the apparatus for automatically receiving said;

impulsesof energy, rotating mechanism at the receiver, a printeroperatedv thereby,

and an electrontubecircuit for maintaining said rotating mechanism at aspeed definitely related to the speed of said rotating ineclianisii'i atsaid transmitter whereby a character represented by a particular groupof said impulses is simultaneously printed.

4. A system of radio communication coinprising in combination atransmitting ap, paratus, a source oi oscillations, rotating mechanismfor causing radiation of said oscillations in groups of impulses ofenergy, -a receivingr apparatus for automatically receiving saidimpulses of energy, rotating' mechanism at the receiver, a printeroperated thereby, a driving motor at both said transmitter and receiverarranged to drive said rotating mechanism, a field winding for saidmotor, an electron tube appa atus having grid, filament .and platecircuits,

lapparatus for automatically receiving said impulses of energy, rotatingmechanism at the receiver, a printer operated thereby, a driving motorat both said transmitter and receiver arranged to drive said rotatingmechanism, a field Winding for said motor,

an electron tube apparatus having grid, filament and plate circuits,means actuated by `sa'id motor for normally charging said grid circuitnegatively, a coil winding connected in said plate circuit andmagnetically cou led to said field winding, means actuate by said motbrunder conditions of increase in'speed for charging said grid circuitpositively whereby said coil winding normally is electrically inert butoperates to increase the -magnetic 'flux emanating from said fieldwinding when said grid eircuit is charged, positively operating the ap.-paratus of said transmitter and receiver at predetermined speed forthelv automatic transmission and reception of signals in print.

6. A system of radio communication comprising in combination atransmitting apparatus, a source of oscillations, rotating mechanism forcausingradiation of' said oscillations in groups of impulses of energy,a receiving apparatus for automatically receiving said impulses ofenergy, rotating mechanism at the receiver, a printer operated thereby,a motor at both said transmitter and receiver-arranged to drive saidrotating mechanism, a field winding for said motor, an electron tubeapparatus having grid, filament and plate circuits, means actuated bysaid motti' under conditions of varyino speed for varying thepolarization of said grid circuit, a coil winding series connected in'sa-id plate circuit and coupledto' said field winding whereby saidfield Winding has mechanism for causing radiation of said os- 'Icillations in groups of impulses of energy, a receiving apparatus forautomatically recciving said impulses of energ rotating'.

mechanism at the receiver, a printer operated thereby, a motor at bothsaid transmitter and receiver arranged to drive said rotating mechanism,a field winding for said motor, anelecti'on tube apparatus having grid,'filament and plate circuits, centrifugal means actuated by said motorunder conditions of vai 7ing speed, a pivotal arm operated by saicentrifugal means, and

electrical means controlledby said arm for varying the olarization ofsaid grid cir,- cuit, a coil winding series connected in said platecircuit and coupled to said field winding whereby said field has itsfield of force increased under conditions of increase in motor speedcausing said motors to operate at predetermined speed at saidtransmitter and receiver for the automatic transmission and reception ofsignals in print.

8. A system of radio communication coinprising in combination means forautomatically transmitting radio frequency energy in groups of impulsesof energy, an electron tube circuit for maintaining thel radiation ofsaid impulses of energy at predetermined speed, a receiving apparatushaving means automatically responding to saidl impulses 'of energy forprinting a character represented by each particular group of impulses,

vrotary mechanism for driving said' automatic means at both saidtransmitter and receiver, centrifugal means connected with said rotarymechanism, a pair of contacts, a switch arm arranged to contact with oneof said contacts when said rotary mechanism is operated at requiredspeed and make connection with said other contact` when said centrifugalmeans 'is actuated, an electron tube apparatus having an input andoutptcircuit, so'urces of energy of opposite polarity connected with saidcontacts and a circuit arrangement whereby said switch arm in making andbreaking said contacts varies the polarity of said -input circuit andmeans in said output circuit for correspondingly controlling the speed'of said rotary mechanism at said transmitter and receiver.

9. A system of radio communication comprising in combination means forautomatically transmitting radio frequency energy in groups of impulsesof energy, an electron tube circuit for maintaining the'radiation ofsaid impulses o f energy at predetermined speed, a receiving apparatushaving means automatically responding to said impulses of energy forprinting a character represented by each particular group of impulses,rotating mechanism for driving said automatic means at both saidtransmitter and receiver,

a centrifugalmeans connected withsaid ro-A tary mechanism, a switch armcarried by said centrifugal means, a pair' of independent contactsarranged to be separately closed by said switch arm, a local source ofpositive polarity connected with one of said contacts, and a localsource of negative polarity connected with the other of said contacts,an

electron tube apparatus having grid, {ilament and plate circuits,connections between .said grid circuit and each of said local sources,and a connection between said filament and said switch arm wherebyvariation in speed causes variation in polarity of said grid circuit,and means in said plate circuit for controlling the speed of said rotarymechanism at said transmitter and receiver.

10. In a radio printing apparatus, the combination with a rotatingdistributor, of an operating mot-or therefor, means for maintaining themotor speed atthe desired rate comprising an electron tube circuit, anda centrifugal governor driven by the motor for controlling said circuit.

11. In a radio printing apparatus, the combination with a rotatingdistributor, of an operating motor' therefor, means for maintaining themotor speed at the desired rate comprising a divided electron tubecircuit arranged to function in a pluralityof different conditions and acentrifugal governor driven by the motor for controlling said circuit.

l2. In a radio printing apparatus, the combination withv a rotatingdistributor, of an operating motor therefor, means for maintaining themotor speed. at the desired rate-comprising an electron tube circuithaving a pair of independent input circuits and a centrifugal governordriven by the motor for controlling connections to each of said circuitsindependently.

In testimony whereof I afiix my signature.

JOHN B. BRADY.

